Phenates

In chemistry, phenolates are salts of phenols . They are formed from phenols through the substitution of the hydrogen atom of the hydroxyl group by metals.

Manufacturing

Sodium phenate

Alkali salts of phenols are formed when phenols are treated with alkali hydroxide solutions. So z. B. Sodium phenolate due to the action of sodium hydroxide on phenol .

properties

Alkali phenolates - such as sodium phenolate - are very strongly hydrolytically split in aqueous solution, i.e. they have a basic reaction. Mineral acids, carboxylic acids or carbon dioxide release the phenol in question from phenolate solutions. Phenolate anions react as strong nucleophiles and can be attacked at both oxygen and carbon positions. In general, attack on the oxygen atom is preferred under kinetically controlled conditions, whereas carbon attack is mainly observed under thermodynamic control.

use

Alkyl aryl ethers can be produced, for example, by the Williamson ether synthesis . For this purpose z. B. Sodium phenolate reacted with alkyl halides , preferably iodides :

${\displaystyle \mathrm {C_{6}H_{5}{-}ONa\ +\ CH_{3}{-}I\longrightarrow \ C_{6}H_{5}{-}O{-}CH_{3}\ +\ NaI} }$

Reaction between sodium phenate and methyl iodide to form anisole and sodium iodide

On an industrial scale, dialkyl sulfates (for example diethyl sulfate to introduce ethyl residues ) can also be used instead of the alkyl halides :

${\displaystyle \mathrm {C_{6}H_{5}{-}ONa\ +\ (H_{3}CO)_{2}{-}SO_{2}\longrightarrow \ C_{6}H_{5}{-}O{-}CH_{3}\ +\ (H_{3}CO)SO_{3}Na} }$

Reaction between sodium phenolate and dimethyl sulfate to form anisole.

Technical production of salicylic acid

Salicylic acid is produced from CO ₂ and sodium phenolate using the Kolbe-Schmitt reaction (also referred to as salicylic acid synthesis for simplicity) :

Individual evidence

1. ↑ ^{a b} Hans-Dieter Jakubke, Ruth Karcher (coordinators): Lexicon of Chemistry in three volumes, Spektrum Verlag, Heidelberg, Volume 3, 1999, ISBN 3-8274-0381-2 , p. 14.
2. ↑ Robert J. Mayer, Martin Breugst, Nathalie Hampel, Armin R. Ofial, Herbert Mayr: Ambident Reactivity of Phenolate Anions Revisited: A Quantitative Approach to Phenolate Reactivities . In: Journal of Organic Chemistry . June 26, 2019. doi : 10.1021 / acs.joc.9b01485 .
3. ^ Hans Beyer and Wolfgang Walter : Organische Chemie , S. Hirzel Verlag, Stuttgart, 1984, pp. 463-464, ISBN 3-7776-0406-2 .